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<h4 class="subsection" id="Modern-GNU-Objective_002dC-Runtime-API"><span>8.1.1 Modern GNU Objective-C Runtime API<a class="copiable-link" href="#Modern-GNU-Objective_002dC-Runtime-API"> &para;</a></span></h4>

<p>The GNU Objective-C runtime provides an API which is similar to the
one provided by the &ldquo;Objective-C 2.0&rdquo; Apple/NeXT Objective-C
runtime.  The API is documented in the public header files of the GNU
Objective-C runtime:
</p>
<ul class="itemize mark-bullet">
<li><samp class="file">objc/objc.h</samp>: this is the basic Objective-C header file,
defining the basic Objective-C types such as <code class="code">id</code>, <code class="code">Class</code>
and <code class="code">BOOL</code>.  You have to include this header to do almost
anything with Objective-C.

</li><li><samp class="file">objc/runtime.h</samp>: this header declares most of the public runtime
API functions allowing you to inspect and manipulate the Objective-C
runtime data structures.  These functions are fairly standardized
across Objective-C runtimes and are almost identical to the Apple/NeXT
Objective-C runtime ones.  It does not declare functions in some
specialized areas (constructing and forwarding message invocations,
threading) which are in the other headers below.  You have to include
<samp class="file">objc/objc.h</samp> and <samp class="file">objc/runtime.h</samp> to use any of the
functions, such as <code class="code">class_getName()</code>, declared in
<samp class="file">objc/runtime.h</samp>.

</li><li><samp class="file">objc/message.h</samp>: this header declares public functions used to
construct, deconstruct and forward message invocations.  Because
messaging is done in quite a different way on different runtimes,
functions in this header are specific to the GNU Objective-C runtime
implementation.

</li><li><samp class="file">objc/objc-exception.h</samp>: this header declares some public
functions related to Objective-C exceptions.  For example functions in
this header allow you to throw an Objective-C exception from plain
C/C++ code.

</li><li><samp class="file">objc/objc-sync.h</samp>: this header declares some public functions
related to the Objective-C <code class="code">@synchronized()</code> syntax, allowing
you to emulate an Objective-C <code class="code">@synchronized()</code> block in plain
C/C++ code.

</li><li><samp class="file">objc/thr.h</samp>: this header declares a public runtime API threading
layer that is only provided by the GNU Objective-C runtime.  It
declares functions such as <code class="code">objc_mutex_lock()</code>, which provide a
platform-independent set of threading functions.

</li></ul>

<p>The header files contain detailed documentation for each function in
the GNU Objective-C runtime API.
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